Question: Is it necessary to replace belts periodically?
Answer: Yes. Although the auto makers don't usually specify
a replacement interval for V-belts or serpentine (flat, multi-ribbed)
belts, most belt manufacturers do recommend periodic replacement
for preventative maintenance. Here's why: the incidence of belt
failure rises sharply in the fourth year of service for the typical
V-belt, and the fifth year for serpentine belts.
What's more, eight out of ten V-belt failures and ten out of ten
serpentine belt failures end up causing a breakdown! That's because
belts have the uncanny knack of always picking the worst possible
moment to fail -- like when you're heading out of town on that
long-awaited fishing trip, when you're hurrying to pick up a hot
date who told you NOT to be late, or when you're giving your dear
mother-in-law a ride to church.
A broken belt is always bad news because when it snaps, all drive
power to whatever it turns is lost. That means the water pump
quits circulating coolant through the engine, the alternator quits
producing amps, the power steering pump ceases to assist steering,
and the air conditioner quits cooling. Many newer vehicles have
a single serpentine belt that drives all of the engine's accessories,
so when it fails everything stops working.
The good news is that replacing the belts periodically can go
a long way towards minimizing the risk of a breakdown caused
by belt failure. After all, it's a lot easier to replace a belt
at your convenience than having the belt fail unexpectedly Heavens
knows where.
For optimum protection, most experts recommend replacing V-belts
every three to four years, or every 36,000 to 48,000 miles. A recommended
replacement interval for serpentine belts would be every four or
five years, or 50,000 miles.
BELT LIFE
The service life of a V-belt depends on mileage as well as load,
tension and heat. Every time a belt passes around a pulley, it
bends and flexes. This produces heat which age hardens the rubber
over time. The wear process can be greatly accelerated if the
belt is loose and slips because any added friction between belt
and pulley makes the belt run even hotter. This can cause glazing
on the faces of the belt and cause it to slip even more. So one
of the most important factors that affects belt life is making
sure it is properly tensioned when it is installed and that the
proper tension is maintained throughout its service life.
Symptoms that may be the result of improper belt tension include:
- Belt squeal, especially on the fan, A/C compressor or power
steering drives.
- A battery that keeps running down (due to belt slippage).
- Excessive sidewall wear on a V-belt that causes it to ride
lower than normal in the pulley grooves.
- Severe cracking along the underside of a V-belt.
- Noisy alternator, power steering pump, air pump, A/C compressor
or water pump bearings (from excessive belt tension).
BELT REPLACEMENT
Replacement V-belts must be the same length and width as the original.
A belt that's too long or too short may not allow enough adjustment
for proper tension. A belt that's too wide or too narrow will
not ride at the right depth in the pulley grooves.
CAUTION: When installing a new belt, do not attempt to "stretch"
it over pulleys. Doing so can break the internal cords causing
the belt to fail. Always loosen the pulleys so there is adequate
clearance to slip the belt over the pulleys.
Once the belt has been installed on the pulleys, a belt gauge
should be used to adjust belt tension to factory specifications.
The old rule of thumb of allowing 1/2 inch of "give"
between the furthest pulleys is not a very accurate guide for
today's engines. So follow the manufacturer's recommendations
for belt tension.
Once tension has been adjusted, it should be rechecked and readjusted
(if necessary) after a short break-in period (say after 500 to
1,000 miles of driving). It should then be checked twice a year
or every 5,000 or 6,000 miles thereafter.
On vehicles with a single serpentine belt, tension is usually
self-adjusted automatically via a spring loaded tensioner. No
additional adjustment is necessary.
If your engine has been eating or twisting belts, misaligned pulleys
may be your problem. Alignment can be checked with a straightedge.
If a pulley is bent or not in the same plane as the rest, the
problem should be corrected otherwise the "bad" pulley
will continue to ruin belts.
